Characterization of hazardous gases released during ion implant processes

The microelectronic revolution has advanced at the expense of using materials which are potentially toxic to humans and damaging to the environment. The particularly reactive and hazardous nature of the dopants used during ion implant processes has generated concerns. Consequently, a number of preventive measures have been implemented to address environmental control and to minimize worker exposure risks. Delivery of dopants using SDS^(R) sources greatly reduced concerns related to gas handling issues. However, there is insufficient information about the nature and volume of gaseous emissions released by ion implanters to assess post-pump environmental and safety hazards. Effluent characterization could also provide an indirect measure of the performance of the implanter and crucial details necessary to customize an abatement solution. This paper summarizes the analyses performed at the exhaust of the ion source roughing pump and cryo pumps of an Applied Materials xR-80 ion implanter. Analyses were performed during standard implant processes using SDS arsine (AsH₃), phosphine (PH₃), boron trifluoride (BF₃), and silicon tetrafluoride (SiF₄) sources. The characterization study was performed in a quantitative, continuous, in-line mode using a Fourier transform infrared spectrophotometer (FTIR). Roughing pump exhaust streams generated using PH₃ and AsH₃ dopants contained no PH₃ and an average of 4% of the initially introduced AsH₃ respectively. Implant processes involving BF ₃ and SiF₄, resulted in over 70% of the initially introduced dopants being released through the roughing pump. Characterization studies during cryo regeneration resulted in the identification and measurement of a number of gas species as a function of time